Error E09

Safety precautions:

1) If you smell gas, leave the building immediately, avoid electrical switches, do not use phones inside, and call the gas emergency number and a Gas Safe engineer.

2) Before doing any work at the boiler isolate electrical supply at the mains. Any internal work or gas valve work must only be done by a Gas Safe registered engineer.

3) Do not remove the boiler casing or attempt internal repairs unless you are qualified. Visual checks from the outside are OK, but opening the appliance is hazardous.

Initial homeowner checks (safe, non-invasive):

1) Note the error pattern: write down E09 and any other codes or LEDs shown and when they occur (on heating, hot water, startup). This helps the engineer.

2) Simple reset: switch off the boiler at the mains for 1–2 minutes, then switch back on and observe if E09 returns. Do not repeatedly reset many times.

3) Check that the gas supply to the property is on and other gas appliances work. If multiple appliances have no gas, contact your gas supplier.

4) Check the boiler room mains supply: any recent power surges or low voltage can cause electronic faults. If the house has tripped RCDs or fuses, restore safely.

5) Check the system water pressure on the boiler gauge (E09 is not normally pressure-related, but very low pressure can cause other faults). Note the pressure and ensure it is in the normal range (refer to your manual).

6) From outside the casing, inspect for obvious signs: scorch marks, burn smell, or melted connectors visible through vents. Do not insert tools or probes.

If the basic checks do not clear the fault, call a Gas Safe engineer. The engineer’s diagnostic and fix steps (for information so you know what to expect):

1) Confirm fault: the engineer will view fault history and repeat tests to reproduce E09 safely.

2) Electrical safety checks: verify correct mains voltage, earth continuity and correct polarity; check for blown fuses and poor connections.

3) Isolate appliance and remove outer case (engineer only): inspect internal wiring, multi-pin connectors and the harness to the gas valve and control box for loose connections, corrosion or burn damage.

4) Live testing (engineer only): with safety precautions in place the engineer will call for gas and measure the control signals and voltages to the gas valve. They will check whether the valve motor/drive receives the correct command and whether the valve responds.

5) Check the control PCB outputs and driver circuits. If the PCB is not commanding the valve correctly or the output stage is defective, the PCB may be faulty.

6) Mechanical check of gas valve: inspect for a stuck or seized valve motor or internal failure. The engineer may attempt to free a stuck valve if safe to do so; if internal damage is found the valve will be replaced.

7) Replace faulty component as necessary: either the gas control valve or the control box (PCB). After replacement the engineer will tighten and secure all connectors, run boiler checks and carry out combustion/gas rate testing where required by regulations.

8) Reassemble and test: ensure the boiler runs through ignition cycles safely, monitor for repeat E09 and confirm stable operation of heating and hot water where applicable.

9) Post-repair safety checks: gas tightness test, combustion check (if valve/gas related work carried out) and confirmation that no other error codes are present.

Final notes and professional recommendation:

- E09 frequently requires parts replacement or PCB diagnosis; these tasks involve gas and live electrical work and must be performed by a Gas Safe registered engineer.

- Do not attempt internal tests or component replacements yourself. If the error persists after the simple external checks or if you see signs of electrical damage or smell gas, switch the boiler off at the mains and isolate gas if safe, then contact a Gas Safe engineer.

- When you contact an engineer, give them the exact error code(s), the conditions it appears under and the results of your basic checks to speed up diagnosis.